1. Field of the Invention
The present invention relates to a display apparatus capable of wide viewing angle display and narrow viewing angle display.
2. Description of the Related Art
A display apparatus to be mounted in an electronic appliance such as a cell phone must be able to switch the range of the visually recognizable visual angle, i.e. viewing angle, of its display between wide range of visual angle and narrow range of visual angle that prevents the display content from being peeked out by anyone other than the user of the display apparatus.
Jpn. Pat. Appln. KOKAI Publication No. 2004-133334 discloses a liquid crystal display apparatus capable of changing the range of viewing angle. The liquid crystal display apparatus includes a viewing angle restricting element, arranged on one surface of a liquid crystal display element, to decrease the visibility from a direction inclined with respect to the front direction of the liquid crystal display element. The liquid crystal display apparatus is thus capable of wide viewing angle display and narrow viewing angle display with a high security that is free from being peeked out by a third party.
The viewing angle restricting element of the liquid crystal display apparatus is provided with segment regions on each of the opposing inner surfaces of a pair of substrates. Electrodes having predetermined shapes are formed to correspond to the respective segment regions. A liquid crystal layer is sealed between the pair of substrates. The liquid crystal molecules of the liquid crystal layer are aligned, in each segment region, in an alignment state having a viewing angle in a direction inclined in one direction with respect to the direction of normal to the liquid crystal element, and an alignment state having a viewing angle in a direction inclined in a direction opposite to the above inclined direction.
With this liquid crystal display apparatus, when no voltage is applied between the electrodes of the viewing angle restricting element, that is, when the viewing angle restricting element is in a non-display state, the display image of the liquid crystal display element can be seen with a wide viewing angle. In contrast to this, when a voltage is applied between the electrodes of the viewing angle restricting element, a display content corresponding to the electrodes with the predetermined shapes of the segment regions emerges, having a viewing angle in the direction inclined with respect to one direction of the viewing angle restricting element and a viewing angle in a direction inclined in the opposite direction appears. When seeing the liquid crystal display apparatus from directions inclined in one direction and the opposite other direction with respect to the front direction, the display content corresponding to the electrodes conceals the display image of the liquid crystal display element. Then, the display image of the liquid crystal display element cannot be recognized from directions inclined toward the one and the other directions. This restricts the apparent viewing angle of the display image to narrow the viewing angle of the display image.
A display panel is overlaid on a viewing angle restricting liquid crystal element having almost the same structure as that of the display panel. This decreases the transmittance of the display element to darken the display content. As the viewing angle restricting liquid crystal element has almost the same structure as that of the display panel, its structure becomes complicated.